Robinson Consultants provided design and construction services for the lining of a 900mm diameter cast iron watermain in the downtown core of Ottawa. This unique project won the Canadian Consulting Engineering Award of Merit

An existing 900mm watermain located on Gloucester Street in the downtown core of Ottawa had failed twice. Both failures caused significant damage to property and disruption to the water supply system. The existing watermain was constructed of cast iron in 1916-1917 at a shallow depth and was considered to be in poor structural condition. The pipe was the principal feedermain servicing the Ottawa urban core area, including Parliament Hill and the Department of National Defense headquarters. Robinson Consultants evaluated available trenchless rehabilitation methods to reduce construction and social costs while minimizing impact on existing utilities and roadway infrastructure. A loose fitting thermoplastic piping system was selected. The reduction in diameter that occurs with this approach met the hydraulic criteria due to the reduced interior roughness of the liner pipe.

A high density polyethylene 750 mm pipe (I.D.) was pulled inside the existing 900 mm pipe after cleaning. The project length was approximately 1350 m and was sliplined in six pulls ranging in length from 130 m to 270 m. A total of fifteen excavations were required for insertion, system interconnections, building services, valves, and hydrants. The fittings were flanged to the HDPE pipe by a combination of fused stub ends and flanged harnesses imported from England. The National Research Council of Canada contributed to this project by conducting three studies to evaluate grouting of the annular space, material mechanics, and long term pipe performance. Traffic control was a major component of this project as all the major north-south arterial roadways in the downtown Ottawa core were affected.